1. Field of the Invention
The present invention relates to a support structure for an elevated railed-vehicle, such as a monorail. The invention concerns, more particularly, an elevated monorail support structure constructed of prefabricated components that may be easily transported to an installation site and assembled together at the installation site. The support structure preferably includes a pile foundation for improved support during seismic activity and to facilitate installation on existing streets and sidewalks without covering or interfering with underground plumbing or utilities.
2. Description of Background Art
Elevated railed-vehicle systems, such as monorail systems, have numerous benefits, particularly in overcrowded urban environments where the surface streets are congested with traffic and traditional forms of mass transportation, such as buses, must compete for space with existing traffic. For example, a dedicated elevated guideway vehicle system operates above city streets and therefore is immune from traffic congestion. It provides a quick and convenient way for moving people around a city, and it actually helps to relieve traffic congestion.
However, existing elevated railed-vehicle systems have several characteristics that preclude their acceptance throughout the world. First, known support structures are heavy and excessively large making them expensive to construct and install. Such structures are difficult to prefabricate at a central manufacturing facility and then transport easily to the location where they will ultimately be installed. Accordingly, the support structures must be individually manufactured on the site where they will be used. The time and expense of manufacturing such structures is a primary contributor to the excessive costs of elevated rail systems. In addition, variations in weather, temperature, and environment at each individual support structure manufacturing site combined with variations associated with continuously having to move and set-up the manufacturing equipment at each site make it difficult to efficiently control the quality and consistency of each manufactured support structure.
Also, because of space limitations in urban environments, it is desirable to position elevated railed-vehicle systems over existing surface streets. However, in such cases, it is difficult to position known support structures for supporting the guideway so as to not interfere with at least one vehicle traffic lane below the guideway. One way to avoid disrupting street traffic is to position such support structures adjacent to existing roads, such as on sidewalks, instead of on the road itself. Such positioning prevents the support structures from blocking at least one lane of traffic.
However, placement of known support structures adjacent to roads is often impractical for at least two reasons. First, known support structures have wide and relatively shallow foundations. Accordingly, they cannot be easily installed adjacent to existing roadways because these foundations would cover existing underground utilities such as sewer and electric lines. Most building codes prevent placing structural foundations over such utilities. Even in cities not having such building code restrictions, it is not desirable to cover existing underground utilities with essentially immovable foundations weighing several tons.
Second, most cities have tall buildings adjacent to its sidewalks. Positioning known support structures on sidewalks would often position the elevated vehicle guideway too close to these buildings. In many cases, a vehicle running on such guideway would not be able to turn without contacting a building.
Finally, known wide and shallow elevated rail support structure foundations do not provide optimal support during seismic activities, such as earthquakes.
FIGS. 1 and 2 show an example of an elevated railed-vehicle system 10 having these characteristics. They depict the Seattle monorail extending from Seattle Center to Westlake Center in Seattle, Wash., U.S.A. This system 10 was constructed in 1962, and includes a traditional spread foundation 12 under street level 14 formed by a block of reinforced concrete weighing approximately 100,000 pounds and being approximately 4 feet high (16), 15 feet wide (18) and 15 feet long (not shown). A T-shaped support 20 includes a central column portion 22, a lower end pedestal portion 24 and an upper T-shaped end portion 26. Two vehicle guideways 28a, 28b are supported one at each end of the T-shaped end portion 26.
The support 20 is one continuous unit constructed of reinforced concrete at the installation site and lifted with cranes so that the pedestal portion may be secured with anchor bolts 30 to the foundation 12. As shown in FIG. 2, because of its size and the requirement to avoid covering any underground utilities, the foundation 12 is positioned below one lane 32 of a four lane road 34 with the support 20 extending from that lane 32, leaving only three lanes available for traffic 36 on the road 34. Moreover, in order for the vehicle 38 to clear buildings 40 adjacent to the road 34, the guideways 28a, 28b must be positioned over the road 34.
Thus, there remains a need for an elevated railed-vehicle support structure and guideway that can be consistently and economically prefabricated off site and easily moved to the installation site, that provides a low profile foundation that can be easily installed without blocking existing underground utilities, and that permits the vehicle rail system to operate effectively over an existing road without requiring the support structure itself to occupy any lanes of that road.
Fulfilling the forgoing needs is the primary objective of the invention. More specific objectives of the invention are to provide an elevated guideway support structure for a railed-vehicle in which the support structure and guideway:
(1) are economical to manufacture, transport and install;
(2) are wear resistant, strong, and durable;
(3) may be prefabricated off-site with known materials and methods;
(4) are constructed of individual, unassembled components sized and shaped for easy transport and assembly;
and also where the support structure:
(5) is shaped to effectively support and elevate a railed-vehicle guideway over an existing road without blocking a lane of vehicle traffic on that road;
(6) is capable of supporting a plurality of railed-vehicle guideways;
(7) effectively supports an elevated railed-vehicle guideway in a cantilevered manner;
(8) includes a foundation that may be installed near existing underground utilities without covering those utilities;
(9) includes a foundation that provides improved support during seismic activities;
(10) provides a low cost, easy to maintain, reliable, relatively simple, and inexpensive solution to the known problems of elevated guideway support structures for a railed-vehicle.
The invention is an improved guideway and support structure for supporting an elevated guideway for a railed-vehicle having individual unassembled components sized for easy transport that may be prefabricated with known materials and methods and transported to and assembled together at the installation site. The support structure is preferably cantilevered and sized to support one or two vehicle guideways. It may include a pile foundation for improved support during seismic activity and to facilitate installation on existing streets and sidewalks without covering or interfering with underground plumbing or utilities.